<!DOCTYPE html>
<head>
  <style>
    img {
      position: absolute;
      left: 100px;
      top: 100px;
    }
  </style>
  <script>
    if (window.testRunner) {
      addEventListener('load', function() {
        // Zoom in three times. Since the image has sizes=50vw it should
        // remain the same size since the viewport shrinks during a zoom.
        testRunner.zoomPageIn();
        testRunner.zoomPageIn();
        testRunner.zoomPageIn();
      });
    }
  </script>
</head>
<body>
  <img src="resources/black.png" sizes="50vw" srcset="resources/black.png 100w">
</body>
